AMMAN, JORDAN –The three middle-aged men sitting in an Indian restaurant in Jordan's capital scarcely look like Islamic revolutionaries. They are smartly dressed in Western-style suits and sip thoughtfully from cans of Pepsi as they share their plan to reshape the Muslim world.

"[President] Bush says that we want to enslave people and oppress their freedom of speech," says Abu Abdullah, a senior member of Hizb ut-Tahrir, the Party of Liberation. "But we want to free all people from being slaves of men and make them slaves of Allah."

Hizb ut-Tahrir says that Muslims should abolish national boundaries within the Islamic world and return to a single Islamic state, known as "the Caliphate," that would stretch from Indonesia to Morocco and contain more than 1.5 billion people.

It's a simple and seductive idea that analysts believe may someday allow the group to rival existing Islamic movements, topple the rulers of Middle Eastern nations, and undermine those seeking to reconcile democracy and Islam and build bridges between East and West.

"A few years ago people laughed at them," says Zeyno Baran, a senior fellow at the Hudson Institute and the leading expert on Hizb ut-Tahrir. "But now that [Osama] bin Laden, [Abu Musab al-] Zarqawi, and other Islamic groups are saying they want to recreate the Caliphate, people are taking them seriously."

Even more moderate Muslim groups such as the Muslim Brotherhood in Egypt pay lip-service to the ideal of reestablishing the Caliphate, leaving less ideological space for Muslims who want to move toward Western models of democracy.

"The Caliphate is a rallying point between the radicals and the more moderate Islamists," says Stephen Ulph, a senior fellow at the Jamestown Foundation. "The idea of a government based on the Caliphate has a historical pedigree and Islamic legitimacy that Western systems of government by their very nature do not have."

But unlike Al Qaeda, Hizb ut-Tahrir believes it can recreate the Caliphate peacefully. Its activists aim to pursuade Muslim political and military leaders that reestablishing the Caliphate is their Islamic duty. Once these leaders invite Hizb ut-Tahrir to take power - effectively staging a military coup - the party would then repeat the process in other countries before linking them up to form a revived Caliphate.

"We spread our ideas by addressing people directly," says Abdullah Shakr, a fluent English-speaker, who, like all three men, spent time in Jordanian jails for membership in the party. "We don't care if the government knows about us, but ... we try not to catch their attention."

The party was founded in Jerusalem in 1953 by a Palestinian judge, Sheikh Taqiuddin Al-Nabhani. He taught that the Muslim world had grown poor and weak ever since the Caliphate was abolished by Turkish leader Kemal Ataturk in 1924.

The Caliphate was created after the death of Islam's founder Muhammad in 632 AD. During the following centuries the Caliphate expanded Islam's territories by conquest and treaty to cover most of the Middle East, Central Asia, and North Africa. As the Ottoman Turks lost ground to the West, they increasingly donned the cloak of the Caliphate. In the 1920s, Muslims throughout the British empire, particularly in India, used the restoration of the Caliphate as an anti-colonial rallying point. "People look back on the Caliphate and see its success as a poor reflection on the condition of the Muslim world today," says Mr. Ulph.

Hizb ut-Tahrir promises that a revived Caliphate will end corruption and bring prosperity - though the group doesn't say how. It will let Muslims challenge, and ultimately conquer, the West, its followers say.

"The Muslim world has resources like oil but it lacks the leadership that will rule us by Islamic law and make this jihad that the whole world is afraid of," says Shakr, a Jordanian member of the group, who says the success of the Caliphate will also encourage more converts to Islam - eventually making the whole world Islamic.

Hizb ut-Tahrir's modern leader is a Jordanian known as Emir Atta Abu Rashta. He lives in a secret location in the Middle East and communicates mainly through the Internet. The party is illegal in all Arab countries as well as Germany. Britain mooted banning the group after last year's London bombings. Ms. Baran wrote in the November issue of Foreign Affairs that the attacks were carried out by members of a Hizb ut-Tahrir splinter group. The British government has not formally accused Hizb ut-Tahrir or Hizb ut-Tahrir splinter groups of involvement. Hizb ut-Tahrir's British branch has condemned both the 7/7 and 9/11 attacks. [ Editor's note: Due to an editing error, the original version did not cite Baran or include Hizb ut-Tahrir's condemnation.]

Hizb ut-Tahrir's critics rarely see the organization as a direct threat, however.

"Many people see Hizb ut-Tahrir's aims as utterly unrealistic," says Nadim Shehadi, a Middle East analyst at Chatham House. "Even their understanding of the Caliphate as a strong, powerful state is questionable. Historically the Caliphate only worked because it was very loose and extremely decentralized."

Many analysts say that real danger is that the group radicalizes its followers who may subsequently graduate into militancy.

Hizb ut-Tahrir is not a mass movement yet, but analysts warn the group has a growing prominence among educated professionals in Europe and the Middle East.

"In Europe they tell Muslims that they have to create parallel societies and that they should not follow European laws," says Ms. Baran. "If this happens it will impossible for people like me to argue that Islam can be democratic."

Baran estimates the group has tens of thousands of followers in Central Asia. "They're stronger in places where people know less about Islam and can't read the Koran in Arabic," she says. "They're not as popular in the Middle East because they don't get involved in the Palestinian cause."

Hizb ut-Tahrir takes a more gradual, long-term strategy for spreading the territory under Muslim rule.

"Islam obliges Muslims to possess power so that they can intimidate - I would not say terrorize - the enemies of Islam," says Abu Mohammed, a Hizb ut-Tahrir activist. "In the beginning, the Caliphate would strengthen itself internally and it wouldn't initiate jihad."

"But after that we would carry Islam as an intellectual call to all the world," says Abu Mohammed, a pseudonym. "And we will make people bordering the Caliphate believe in Islam. Or if they refuse then we'll ask them to be ruled by Islam."

And after that? Abu Mohammed pauses and fiddles with his Pepsi before replying.

"And if after all discussions and negotiations they still refuse, then the last resort will be a jihad to spread the spirit of Islam and the rule of Islam," he says, smiling. "This is done in the interests of all people to get them out of darkness and into light."